Allight then I think this is standard operation you just have some big models and the patched exe tries to keep them in memory to help mintaian fps (in the tracks this is very helpful).
nevertheless you can force the memory cleaning in the catalog
Add this to the catalog.enter()

RawEdit.setI(0x00618670,1);

and this to catalog.exit()

RawEdit.setI(0x00618670,0);

use the d3d9.dll and the Slrr_GI.exe that came with the patch and it will force the memory to minimum in the catalogue aswell.